1 Upgrading to Rails 3.2
If you're upgrading an existing application, it's a great idea to have good test coverage before going in. You should also first upgrade to Rails 3.1 in case you haven't and make sure your application still runs as expected before attempting an update to Rails 3.2. Then take heed of the following changes:
1.1 Rails 3.2 requires at least Ruby 1.8.7
Rails 3.2 requires Ruby 1.8.7 or higher. Support for all of the previous Ruby versions has been dropped officially and you should upgrade as early as possible. Rails 3.2 is also compatible with Ruby 1.9.2.
Note that Ruby 1.8.7 p248 and p249 have marshalling bugs that crash Rails. Ruby Enterprise Edition has these fixed since the release of 1.8.7-2010.02. On the 1.9 front, Ruby 1.9.1 is not usable because it outright segfaults, so if you want to use 1.9.x, jump on to 1.9.2 or 1.9.3 for smooth sailing.
1.2 What to update in your apps
Update your
Gemfile
to depend onrails = 3.2.0
sass-rails ~> 3.2.3
coffee-rails ~> 3.2.1
uglifier >= 1.0.3
Rails 3.2 deprecates
vendor/plugins
and Rails 4.0 will remove them completely. You can start replacing these plugins by extracting them as gems and adding them in yourGemfile
. If you choose not to make them gems, you can move them into, say,lib/my_plugin/*
and add an appropriate initializer inconfig/initializers/my_plugin.rb
.There are a couple of new configuration changes you'd want to add in
config/environments/development.rb
:# Raise exception on mass assignment protection for Active Record modelsconfig.active_record.mass_assignment_sanitizer = :strict# Log the query plan for queries taking more than this (works# with SQLite, MySQL, and PostgreSQL)config.active_record.auto_explain_threshold_in_seconds = 0.5
The
mass_assignment_sanitizer
config also needs to be added inconfig/environments/test.rb
:# Raise exception on mass assignment protection for Active Record modelsconfig.active_record.mass_assignment_sanitizer = :strict
1.3 What to update in your engines
Replace the code beneath the comment in script/rails
with the following content:
ENGINE_ROOT = File.expand_path('../..', __FILE__)ENGINE_PATH = File.expand_path('../../lib/your_engine_name/engine', __FILE__)require "rails/all"require "rails/engine/commands"
2 Creating a Rails 3.2 application
# You should have the 'rails' RubyGem installed$ rails new myapp$ cd myapp
2.1 Vendoring Gems
Rails now uses a Gemfile
in the application root to determine the gems you require for your application to start. This Gemfile
is processed by the Bundler gem, which then installs all your dependencies. It can even install all the dependencies locally to your application so that it doesn't depend on the system gems.
More information: Bundler homepage
2.2 Living on the Edge
Bundler
and Gemfile
makes freezing your Rails application easy as pie with the new dedicated bundle
command. If you want to bundle straight from the Git repository, you can pass the --edge
flag:
$ rails new myapp --edge
If you have a local checkout of the Rails repository and want to generate an application using that, you can pass the --dev
flag:
$ ruby /path/to/rails/railties/bin/rails new myapp --dev
3 Major Features
Rails 3.2 comes with a development mode that's noticeably faster. Inspired by Active Reload, Rails reloads classes only when files actually change. The performance gains are dramatic on a larger application. Route recognition also got a bunch faster thanks to the new Journey engine.
3.2 Automatic Query Explains
Rails 3.2 comes with a nice feature that explains queries generated by Arel by defining an explain
method in ActiveRecord::Relation
. For example, you can run something like puts Person.active.limit(5).explain
and the query Arel produces is explained. This allows to check for the proper indexes and further optimizations.
Queries that take more than half a second to run are automatically explained in the development mode. This threshold, of course, can be changed.
3.3 Tagged Logging
When running a multi-user, multi-account application, it's a great help to be able to filter the log by who did what. TaggedLogging in Active Support helps in doing exactly that by stamping log lines with subdomains, request ids, and anything else to aid debugging such applications.
4 Documentation
From Rails 3.2, the Rails guides are available for the Kindle and free Kindle Reading Apps for the iPad, iPhone, Mac, Android, etc.
5 Railties
Speed up development by only reloading classes if dependencies files changed. This can be turned off by setting
config.reload_classes_only_on_change
to false.New applications get a flag
config.active_record.auto_explain_threshold_in_seconds
in the environments configuration files. With a value of0.5
indevelopment.rb
and commented out inproduction.rb
. No mention intest.rb
.Added
config.exceptions_app
to set the exceptions application invoked by theShowException
middleware when an exception happens. Defaults toActionDispatch::PublicExceptions.new(Rails.public_path)
.Added a
DebugExceptions
middleware which contains features extracted fromShowExceptions
middleware.Display mounted engines' routes in
rake routes
.Allow to change the loading order of railties with
config.railties_order
like:config.railties_order = [Blog::Engine, :main_app, :all]
Scaffold returns 204 No Content for API requests without content. This makes scaffold work with jQuery out of the box.
Update
Rails::Rack::Logger
middleware to apply any tags set inconfig.log_tags
toActiveSupport::TaggedLogging
. This makes it easy to tag log lines with debug information like subdomain and request id -- both very helpful in debugging multi-user production applications.Default options to
rails new
can be set in~/.railsrc
. You can specify extra command-line arguments to be used every timerails new
runs in the.railsrc
configuration file in your home directory.Add an alias
d
fordestroy
. This works for engines too.Attributes on scaffold and model generators default to string. This allows the following:
bin/rails g scaffold Post title body:text author
Allow scaffold/model/migration generators to accept "index" and "uniq" modifiers. For example,
$ bin/rails g scaffold Post title:string:index author:uniq price:decimal{7,2}
See AlsoRuby 3.2.0 Preview 2 Releasedwill create indexes for
title
andauthor
with the latter being a unique index. Some types such as decimal accept custom options. In the example,price
will be a decimal column with precision and scale set to 7 and 2 respectively.Turn gem has been removed from default
Gemfile
.Remove old plugin generator
rails generate plugin
in favor ofrails plugin new
command.Remove old
config.paths.app.controller
API in favor ofconfig.paths["app/controller"]
.
5.1 Deprecations
Rails::Plugin
is deprecated and will be removed in Rails 4.0. Instead of adding plugins tovendor/plugins
use gems or bundler with path or git dependencies.
6 Action Mailer
Upgraded
mail
version to 2.4.0.Removed the old Action Mailer API which was deprecated since Rails 3.0.
7 Action Pack
7.1 Action Controller
Make
ActiveSupport::Benchmarkable
a default module forActionController::Base,
so the#benchmark
method is once again available in the controller context like it used to be.Added
:gzip
option tocaches_page
. The default option can be configured globally usingpage_cache_compression
.Rails will now use your default layout (such as "layouts/application") when you specify a layout with
:only
and:except
condition, and those conditions fail.class CarsController layout 'single_car', :only => :showend
Rails will use
layouts/single_car
when a request comes in:show
action, and uselayouts/application
(orlayouts/cars
, if exists) when a request comes in for any other actions.form_for
is changed to use#{action}_#{as}
as the CSS class and id if:as
option is provided. Earlier versions used#{as}_#{action}
.ActionController::ParamsWrapper
on Active Record models now only wrapattr_accessible
attributes if they were set. If not, only the attributes returned by the class methodattribute_names
will be wrapped. This fixes the wrapping of nested attributes by adding them toattr_accessible
.Log "Filter chain halted as CALLBACKNAME rendered or redirected" every time a before callback halts.
ActionDispatch::ShowExceptions
is refactored. The controller is responsible for choosing to show exceptions. It's possible to overrideshow_detailed_exceptions?
in controllers to specify which requests should provide debugging information on errors.Responders now return 204 No Content for API requests without a response body (as in the new scaffold).
ActionController::TestCase
cookies is refactored. Assigning cookies for test cases should now usecookies[]
cookies[:email] = 'user@example.com'get :indexassert_equal 'user@example.com', cookies[:email]
To clear the cookies, use
clear
.cookies.clearget :indexassert_nil cookies[:email]
We now no longer write out HTTP_COOKIE and the cookie jar is persistent between requests so if you need to manipulate the environment for your test you need to do it before the cookie jar is created.
send_file
now guesses the MIME type from the file extension if:type
is not provided.MIME type entries for PDF, ZIP and other formats were added.
Allow
fresh_when/stale?
to take a record instead of an options hash.Changed log level of warning for missing CSRF token from
:debug
to:warn
.Assets should use the request protocol by default or default to relative if no request is available.
7.1.1 Deprecations
Deprecated implied layout lookup in controllers whose parent had an explicit layout set:
class ApplicationController layout "application"endclass PostsController < ApplicationControllerend
In the example above,
PostsController
will no longer automatically look up for a posts layout. If you need this functionality you could either removelayout "application"
fromApplicationController
or explicitly set it tonil
inPostsController
.Deprecated
ActionController::UnknownAction
in favor ofAbstractController::ActionNotFound
.Deprecated
ActionController::DoubleRenderError
in favor ofAbstractController::DoubleRenderError
.Deprecated
method_missing
in favor ofaction_missing
for missing actions.Deprecated
ActionController#rescue_action
,ActionController#initialize_template_class
andActionController#assign_shortcuts
.
7.2 Action Dispatch
Add
config.action_dispatch.default_charset
to configure default charset forActionDispatch::Response
.Added
ActionDispatch::RequestId
middleware that'll make a unique X-Request-Id header available to the response and enables theActionDispatch::Request#uuid
method. This makes it easy to trace requests from end-to-end in the stack and to identify individual requests in mixed logs like Syslog.The
ShowExceptions
middleware now accepts an exceptions application that is responsible to render an exception when the application fails. The application is invoked with a copy of the exception inenv["action_dispatch.exception"]
and with thePATH_INFO
rewritten to the status code.Allow rescue responses to be configured through a railtie as in
config.action_dispatch.rescue_responses
.
7.2.1 Deprecations
- Deprecated the ability to set a default charset at the controller level, use the new
config.action_dispatch.default_charset
instead.
7.3 Action View
Add
button_tag
support toActionView::Helpers::FormBuilder
. This support mimics the default behavior ofsubmit_tag
.<%= form_for @post do |f| %> <%= f.button %><% end %>
Date helpers accept a new option
:use_two_digit_numbers => true
, that renders select boxes for months and days with a leading zero without changing the respective values. For example, this is useful for displaying ISO 8601-style dates such as '2011-08-01'.You can provide a namespace for your form to ensure uniqueness of id attributes on form elements. The namespace attribute will be prefixed with underscore on the generated HTML id.
<%= form_for(@offer, :namespace => 'namespace') do |f| %> <%= f.label :version, 'Version' %>: <%= f.text_field :version %><% end %>
Limit the number of options for
select_year
to 1000. Pass:max_years_allowed
option to set your own limit.content_tag_for
anddiv_for
can now take a collection of records. It will also yield the record as the first argument if you set a receiving argument in your block. So instead of having to do this:@items.each do |item| content_tag_for(:li, item) do Title: <%= item.title %> endend
You can do this:
content_tag_for(:li, @items) do |item| Title: <%= item.title %>end
Added
font_path
helper method that computes the path to a font asset inpublic/fonts
.
7.3.1 Deprecations
- Passing formats or handlers to render :template and friends like
render :template => "foo.html.erb"
is deprecated. Instead, you can provide :handlers and :formats directly as options:render :template => "foo", :formats => [:html, :js], :handlers => :erb
.
7.4 Sprockets
- Adds a configuration option
config.assets.logger
to control Sprockets logging. Set it tofalse
to turn off logging and tonil
to default toRails.logger
.
8 Active Record
Boolean columns with 'on' and 'ON' values are type cast to true.
When the
timestamps
method creates thecreated_at
andupdated_at
columns, it makes them non-nullable by default.Implemented
ActiveRecord::Relation#explain
.Implements
ActiveRecord::Base.silence_auto_explain
which allows the user to selectively disable automatic EXPLAINs within a block.Implements automatic EXPLAIN logging for slow queries. A new configuration parameter
config.active_record.auto_explain_threshold_in_seconds
determines what's to be considered a slow query. Setting that to nil disables this feature. Defaults are 0.5 in development mode, and nil in test and production modes. Rails 3.2 supports this feature in SQLite, MySQL (mysql2 adapter), and PostgreSQL.Added
ActiveRecord::Base.store
for declaring simple single-column key/value stores.class User < ActiveRecord::Base store :settings, accessors: [ :color, :homepage ]endu = User.new(color: 'black', homepage: '37signals.com')u.color # Accessor stored attributeu.settings[:country] = 'Denmark' # Any attribute, even if not specified with an accessor
Added ability to run migrations only for a given scope, which allows to run migrations only from one engine (for example to revert changes from an engine that need to be removed).
rake db:migrate SCOPE=blog
Migrations copied from engines are now scoped with engine's name, for example
01_create_posts.blog.rb
.Implemented
ActiveRecord::Relation#pluck
method that returns an array of column values directly from the underlying table. This also works with serialized attributes.Client.where(:active => true).pluck(:id)# SELECT id from clients where active = 1
Generated association methods are created within a separate module to allow overriding and composition. For a class named MyModel, the module is named
MyModel::GeneratedFeatureMethods
. It is included into the model class immediately after thegenerated_attributes_methods
module defined in Active Model, so association methods override attribute methods of the same name.Add
ActiveRecord::Relation#uniq
for generating unique queries.Client.select('DISTINCT name')
..can be written as:
Client.select(:name).uniq
This also allows you to revert the uniqueness in a relation:
Client.select(:name).uniq.uniq(false)
Support index sort order in SQLite, MySQL and PostgreSQL adapters.
Allow the
:class_name
option for associations to take a symbol in addition to a string. This is to avoid confusing newbies, and to be consistent with the fact that other options like:foreign_key
already allow a symbol or a string.has_many :clients, :class_name => :Client # Note that the symbol need to be capitalized
In development mode,
db:drop
also drops the test database in order to be symmetric withdb:create
.Case-insensitive uniqueness validation avoids calling LOWER in MySQL when the column already uses a case-insensitive collation.
Transactional fixtures enlist all active database connections. You can test models on different connections without disabling transactional fixtures.
Add
first_or_create
,first_or_create!
,first_or_initialize
methods to Active Record. This is a better approach over the oldfind_or_create_by
dynamic methods because it's clearer which arguments are used to find the record and which are used to create it.User.where(:first_name => "Scarlett").first_or_create!(:last_name => "Johansson")
Added a
with_lock
method to Active Record objects, which starts a transaction, locks the object (pessimistically) and yields to the block. The method takes one (optional) parameter and passes it tolock!
.This makes it possible to write the following:
class Order < ActiveRecord::Base def cancel! transaction do lock! # ... cancelling logic end endend
as:
class Order < ActiveRecord::Base def cancel! with_lock do # ... cancelling logic end endend
8.1 Deprecations
Automatic closure of connections in threads is deprecated. For example the following code is deprecated:
Thread.new { Post.find(1) }.join
It should be changed to close the database connection at the end of the thread:
Thread.new { Post.find(1) Post.connection.close}.join
Only people who spawn threads in their application code need to worry about this change.
The
set_table_name
,set_inheritance_column
,set_sequence_name
,set_primary_key
,set_locking_column
methods are deprecated. Use an assignment method instead. For example, instead ofset_table_name
, useself.table_name=
.class Project < ActiveRecord::Base self.table_name = "project"end
Or define your own
self.table_name
method:class Post < ActiveRecord::Base def self.table_name "special_" + super endendPost.table_name # => "special_posts"
9 Active Model
Add
ActiveModel::Errors#added?
to check if a specific error has been added.Add ability to define strict validations with
strict => true
that always raises exception when fails.Provide mass_assignment_sanitizer as an easy API to replace the sanitizer behavior. Also support both :logger (default) and :strict sanitizer behavior.
9.1 Deprecations
Deprecated
define_attr_method
inActiveModel::AttributeMethods
because this only existed to support methods likeset_table_name
in Active Record, which are themselves being deprecated.Deprecated
Model.model_name.partial_path
in favor ofmodel.to_partial_path
.
10 Active Resource
- Redirect responses: 303 See Other and 307 Temporary Redirect now behave like 301 Moved Permanently and 302 Found.
11 Active Support
Added
ActiveSupport:TaggedLogging
that can wrap any standardLogger
class to provide tagging capabilities.Logger = ActiveSupport::TaggedLogging.new(Logger.new(STDOUT))Logger.tagged("BCX") { Logger.info "Stuff" }# Logs "[BCX] Stuff"Logger.tagged("BCX", "Jason") { Logger.info "Stuff" }# Logs "[BCX] [Jason] Stuff"Logger.tagged("BCX") { Logger.tagged("Jason") { Logger.info "Stuff" } }# Logs "[BCX] [Jason] Stuff"
The
beginning_of_week
method inDate
,Time
andDateTime
accepts an optional argument representing the day in which the week is assumed to start.ActiveSupport::Notifications.subscribed
provides subscriptions to events while a block runs.Defined new methods
Module#qualified_const_defined?
,Module#qualified_const_get
andModule#qualified_const_set
that are analogous to the corresponding methods in the standard API, but accept qualified constant names.Added
#deconstantize
which complements#demodulize
in inflections. This removes the rightmost segment in a qualified constant name.Added
safe_constantize
that constantizes a string but returnsnil
instead of raising an exception if the constant (or part of it) does not exist.ActiveSupport::OrderedHash
is now marked as extractable when usingArray#extract_options!
.Added
Array#prepend
as an alias forArray#unshift
andArray#append
as an alias forArray#<<
.The definition of a blank string for Ruby 1.9 has been extended to Unicode whitespace. Also, in Ruby 1.8 the ideographic space U`3000 is considered to be whitespace.
The inflector understands acronyms.
Added
Time#all_day
,Time#all_week
,Time#all_quarter
andTime#all_year
as a way of generating ranges.Event.where(:created_at => Time.now.all_week)Event.where(:created_at => Time.now.all_day)
Added
instance_accessor: false
as an option toClass#cattr_accessor
and friends.ActiveSupport::OrderedHash
now has different behavior for#each
and#each_pair
when given a block accepting its parameters with a splat.Added
ActiveSupport::Cache::NullStore
for use in development and testing.Removed
ActiveSupport::SecureRandom
in favor ofSecureRandom
from the standard library.
11.1 Deprecations
ActiveSupport::Base64
is deprecated in favor of::Base64
.Deprecated
ActiveSupport::Memoizable
in favor of Ruby memoization pattern.Module#synchronize
is deprecated with no replacement. Please use monitor from ruby's standard library.Deprecated
ActiveSupport::MessageEncryptor#encrypt
andActiveSupport::MessageEncryptor#decrypt
.ActiveSupport::BufferedLogger#silence
is deprecated. If you want to squelch logs for a certain block, change the log level for that block.ActiveSupport::BufferedLogger#open_log
is deprecated. This method should not have been public in the first place.ActiveSupport::BufferedLogger's
behavior of automatically creating the directory for your log file is deprecated. Please make sure to create the directory for your log file before instantiating.ActiveSupport::BufferedLogger#auto_flushing
is deprecated. Either set the sync level on the underlying file handle like this. Or tune your filesystem. The FS cache is now what controls flushing.f = File.open('foo.log', 'w')f.sync = trueActiveSupport::BufferedLogger.new f
ActiveSupport::BufferedLogger#flush
is deprecated. Set sync on your filehandle, or tune your filesystem.
12 Credits
See the full list of contributors to Rails for the many people who spent many hours making Rails, the stable and robust framework it is. Kudos to all of them.
Rails 3.2 Release Notes were compiled by Vijay Dev.
Feedback
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Please contribute if you see any typos or factual errors. To get started, you can read our documentation contributions section.
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